JP3600754B2 - Iron oxide particle powder - Google Patents
Iron oxide particle powder Download PDFInfo
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- JP3600754B2 JP3600754B2 JP12504299A JP12504299A JP3600754B2 JP 3600754 B2 JP3600754 B2 JP 3600754B2 JP 12504299 A JP12504299 A JP 12504299A JP 12504299 A JP12504299 A JP 12504299A JP 3600754 B2 JP3600754 B2 JP 3600754B2
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- iron oxide
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- oxide particles
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- 239000002245 particle Substances 0.000 title claims description 141
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 title claims description 94
- 239000000843 powder Substances 0.000 title claims description 28
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 6
- 230000005415 magnetization Effects 0.000 claims description 6
- 239000002253 acid Substances 0.000 claims description 2
- 229910052742 iron Inorganic materials 0.000 claims description 2
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 56
- 230000000052 comparative effect Effects 0.000 description 18
- 238000002156 mixing Methods 0.000 description 7
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 238000001035 drying Methods 0.000 description 5
- 238000001914 filtration Methods 0.000 description 5
- 238000012856 packing Methods 0.000 description 5
- 238000010298 pulverizing process Methods 0.000 description 5
- 239000011347 resin Substances 0.000 description 5
- 229920005989 resin Polymers 0.000 description 5
- 239000002002 slurry Substances 0.000 description 5
- 238000005406 washing Methods 0.000 description 5
- 238000011161 development Methods 0.000 description 4
- 230000005484 gravity Effects 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000007664 blowing Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 239000011790 ferrous sulphate Substances 0.000 description 2
- 235000003891 ferrous sulphate Nutrition 0.000 description 2
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 2
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 2
- 239000000049 pigment Substances 0.000 description 2
- 239000012798 spherical particle Substances 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000012876 carrier material Substances 0.000 description 1
- 229910021506 iron(II) hydroxide Inorganic materials 0.000 description 1
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 description 1
- 238000004898 kneading Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
Landscapes
- Compounds Of Iron (AREA)
- Pigments, Carbon Blacks, Or Wood Stains (AREA)
- Paints Or Removers (AREA)
- Developing Agents For Electrophotography (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、酸化鉄粒子粉末に関し、詳しくは異形状である球状酸化鉄粒子と八面体酸化鉄粒子とを混在させることにより、流動性、分散性、ハンドリング性等の諸特性をバランスよく向上させた、特に静電複写磁性トナー用材料粉、静電潜像現像用キャリア用材料粉、塗料用黒色顔料粉等の用途に主に用いられる酸化鉄粒子粉末に関する。
【０００２】
【従来の技術及び発明が解決しようとする課題】
最近、電子写真複写機、プリンター等の磁性トナー用材料として、水溶液反応による酸化鉄粒子が広く利用されている。
【０００３】
磁性トナーとしては各種の一般的現像特性が要求されるが、近年、電子写真技術の発達により、特にデジタル技術を用いた複写機、プリンターが急速に発達し、要求特性がより高度になってきた。
【０００４】
すなわち、従来の文字以外にもグラフィックや写真等の出力も要求されており、特にプリンターの中には１インチ当たり１２００ドット以上の能力のものも現れ、感光体上の潜像はより緻密になってきている。そのため、現像での細線再現性の高さが強く要求されている。
【０００５】
また、それに伴うトナーも小粒径化されており、より一層の酸化鉄粒子の樹脂への分散が要求されている。
【０００６】
一般的に、トナー、キャリア、顔料を製造する際に、酸化鉄粒子と樹脂の計量、混合、混練を行う。その中で、分散性をよくするためには、計量時又は混合後の混練機への供給性、比重の低い樹脂との混合性をよくする必要がある。一方、高解像度化が進み、残留磁化の低いものが好まれており、またトナーの小粒径化に伴い、それに使用される酸化鉄粒子も小粒径化が必要である。
【０００７】
酸化鉄粒子の比重は、樹脂より重く混合時に分離する可能性があるので、振動があっても嵩密度の低いものであれば、比重の低いものとの混合性を向上することができ、ひいては混練後の分散性を向上することができる。また、そういうものは輸送時にも粉体がしまりにくく、取り扱い性も良好である。
【０００８】
しかし、一般的に球状酸化鉄粒子が低残留磁化であることが広く知られているが、球状品は通常最密充填を取りやすく嵩密度が高くなる傾向があり、流動性の面でも問題があった。流動性の改良については従来から種々の提案が試みられているが、その結果として粉体の流動性は向上するが、嵩密度がさらに高くなる傾向にあった。
【０００９】
また、酸化鉄粒子の代表的な形状として八面体がある。八面体の酸化鉄粒子は、嵩密度が一般的に低いが、その形状より残留磁化が高く、細線再現性に問題があった。
【００１０】
このように、流動性が高く、かつ充填密度が低く、しかも磁気特性に優れた酸化鉄粒子は未だ提供されていない。
【００１１】
従って、本発明の目的は、流動性が高く、かつ充填密度が低く、しかも磁気特性に優れた酸化鉄粒子粉末を提供することにある。
【００１２】
【課題を解決するための手段】
本発明者らは、検討の結果、球状と八面体の酸化鉄粒子を混在させることによって、上記目的が達成し得ることを知見した。
【００１３】
本発明は、上記知見に基づきなされたもので、球状酸化鉄粒子と八面体酸化鉄粒子が混在する酸化鉄粒子粉末であって、
個数平均粒径が０．１５〜０．５μｍ、かつ全個数に対する八面体酸化鉄粒子の存在個数率［八面体酸化鉄粒子個数／（球状酸化鉄粒子個数＋八面体酸化鉄粒子個数）×１００］が５〜９０％で、その中の球状酸化鉄粒子の平均粒径をＸμｍ、八面体酸化鉄粒子の平均粒径をＹμｍ、八面体酸化鉄粒子の存在個数率Ｚ（％）とした時、下記式（１）を満足することを特徴とする酸化鉄粒子粉末を提供するものである。
１０≦（５．２／６×πＹ 3 Ｚ／１００）／［（５．２／６×πＹ 3 Ｚ／１００）＋（５．２／６×πＸ 3 （１００−Ｚ）／１００］×１００・・・・・（１）
【００１４】
【発明の実施の形態】
以下、本発明の実施の形態について説明する。
本発明でいう酸化鉄粒子とは、好ましくはマグネタイトを主成分とするものであり、ケイ素、アルミニウム、チタン等の各種有効元素含有するもの、あるいはこれら有効元素で被覆されたものも含まれる。以下の説明では、酸化鉄粒子としてその代表的なものであるマグネタイト粒子について説明する。また、酸化鉄粒子又はマグネタイト粒子というときには、その内容によって個々の粒子又はその集合のいずれも意味する。また、酸化鉄粒子粉末又はマグネタイト粒子粉末とは、形状、粒径の異なる酸化鉄粒子又はマグネタイト粒子が混在したものをいう。
【００１５】
本発明のマグネタイト粒子粉末は、球状マグネタイト粒子と八面体マグネタイト粒子が混在したものである。ここで球状とは、走査型電子顕微鏡で観察したときに、角や辺がなく、長軸／短軸の比率が１〜１．２のものをいう。また、八面体とは、走査型電子顕微鏡で観察したときに、角と辺を持ち、一つの角に辺を４つ持つものをいう。この球状又は八面体のマグネタイト粒子は、水酸化第一鉄スラリーを酸化する際のｐＨを制御することにより得られる。
【００１６】
本発明のマグネタイト粒子粉末は、個数平均粒径が０．１５〜０．５μｍである。また、全個数に対する八面体マグネタイト粒子の存在個数率［八面体マグネタイト粒子個数／（球状マグネタイト粒子個数＋八面体マグネタイト粒子個数）×１００］が５〜９０％で、その中の球状マグネタイト粒子の平均粒径をＸμｍ、八面体マグネタイト粒子の平均粒径をＹμｍ、八面体マグネタイト粒子の存在個数率Ｚ（％）とした時、下記式（１）を満足する。
１０≦（５．２／６×πＹ3Ｚ／１００）／［（５．２／６×πＹ3Ｚ／１００）＋（５．２／６×πＸ3（１００−Ｚ）／１００］×１００・・・・・（１）
【００１７】
八面体マグネタイト粒子の存在個数率は、５〜９０％、好ましくは１６〜８０％である。この存在個数率が５％未満、又は９０％を超える場合、流動性の改善効果が少ない。
【００１８】
何故、異形状粒子が混在すると流動性が改善されるかについては定かではないが、活性点の異なる粒子の混在により、コロの原理が作用していることが推測される。
【００１９】
また、上記式（１）は、マグネタイト粒子粉末中の粒子すべてを球状粒子と考えた場合に、体積と真比重よりマグネタイト粒子粉末中の八面体粒子の重量比を計算したものである。この式（１）を満たさない場合、すなわち八面体マグネタイト粒子の重量存在率が１０重量％未満の場合、タップ密度が高くなり、輸送中の粉体にしまりが生じ、以降の取扱い性が悪くなる上、樹脂との混合性が不良となる。
【００２０】
本発明のマグネタイト粒子粉末は、タップ密度が１．４ｇ／ｃｍ3以下であることが必要である。タップ密度が１．４ｇ／ｃｍ3を超えると充填密度の上昇を抑えることができない。また、残留磁化（σｒ）は、磁気凝集による流動性への影響を考慮すると８Ａｍ 2 ／ｋｇ（ｅｍｕ／ｇ）以下が好ましい。
【００２１】
本発明のマグネタイト粒子粉末は、流動性の向上という観点から、安息角が好ましくは４２°以下、さらに好ましくは４０°以下である。
【００２２】
【実施例】
以下、実施例等に基づき本発明を具体的に説明する。なお、本発明は八面体粒子と球状粒子が混在していることが重要であり、かかる事例に限定されるものではない。
【００２３】
〔比較例１〕
Ｆｅ２＋２．０ｍｏｌ／リットルを含む硫酸第一鉄水溶液５０リットルと、５．０ｍｏｌ／リットルの水酸化ナトリウム水溶液３６リットルを混合撹拌した。この時のｐＨは６．５であった。そのスラリーを８５℃に維持しながら３０リットル／ｍｉｎの空気を吹き込み、ｐＨを５〜９に維持して反応を終了させた。得られた生成粒子は、通常の濾過、洗浄、乾燥、粉砕工程により処理し、球状マグネタイト粒子を得た。
【００２４】
〔比較例２及び３〕
比較例１と同様の反応において、空気吹き込み量を５０リットル／ｍｉｎ（比較例２）、７０リットル／ｍｉｎ（比較例３）とし、所望の粒径の生成粒子を得た。得られた生成粒子は通常の濾過、洗浄、乾燥、粉砕工程により処理し、球状マグネタイト粒子を得た。
【００２５】
〔比較例４〕
Ｆｅ２＋２．０ｍｏｌ／リットルを含む硫酸第一鉄水溶液５０リットルと、５．２ｍｏｌ／リットルの水酸化ナトリウム水溶液４０リットルを混合撹拌した。この時のｐＨは１１であった。そのスラリーを８５℃に維持しながら３０リットル／ｍｉｎの空気を吹き込み、ｐＨを１０以上にて反応を終了させた。得られた生成粒子は、通常の濾過、洗浄、乾燥、粉砕工程により処理し、八面体マグネタイト粒子を得た。
【００２６】
〔比較例５及び６〕
比較例４と同様の反応において、空気吹き込み量を４０リットル／ｍｉｎ（比較例２）、５０リットル／ｍｉｎ（比較例３）とし、所望の粒径の生成粒子を得た。得られた生成粒子は通常の濾過、洗浄、乾燥、粉砕工程により処理し、八面体マグネタイト粒子を得た。
【００２７】
〔実施例１〕
比較例１の球状マグネタイト粒子７００ｇ、比較例４の八面体マグネタイト粒子３００ｇをＶ型ブレンダーを用い、２０分間混合して球状マグネタイト粒子と八面体マグネタイト粒子の混在するマグネタイト粒子粉末を得た。
【００２８】
〔実施例２〜２６〕
表２〜３に示すマグネタイト粒子粉末となるように、比較例１〜６のマグネタイト粒子を用い、総重量１０ｋｇのマグネタイト粒子を実施例１と同様にＶ型ブレンダーで混合し、マグネタイト粒子粉末を得た。
【００２９】
〔実施例２７〕
比較例１の反応終了後のスラリー７リットルと比較例４の反応終了後のスラリー３リットルを混合し、通常の濾過、洗浄、乾燥、粉砕工程により処理し、マグネタイト粒子粉末を得た。
【００３０】
このようにして得られた比較例１〜６のマグネタイト粒子又は実施例１〜２７のマグネタイト粒子粉末について、下記の評価（平均粒径、全個数に対する八面体マグネタイト粒子の存在個数率、式（１）による八面体マグネタイト粒子の重量存在率、磁気特性、タップ密度、安息角）を行った。結果を表１〜３に示す。
【００３１】
＜評価方法＞
（１）平均粒径
走査型電子顕微鏡にて３万倍の写真を撮影し、２００個測定し、フィレ径にてマグネタイト粒子粉末の個数平均を求めた。その時に八面体マグネタイト粒子、球状マグネタイト粒子の個数もチェックした。また、各形状の平均粒径はそれぞれの形状の測定を１００個測定し、各形状の個数平均粒径を求めた。
（２）全個数に対する八面体マグネタイト粒子の存在個数率
上記（１）にてマグネタイト粒子粉末の平均粒径測定時にチェックした各形状の個数を用い、八面体マグネタイト粒子個数／（球状マグネタイト粒子個数＋八面体マグネタイト粒子個数）×１００で求めた。
（３）式（１）による八面体マグネタイト粒子の重量存在率
球状マグネタイト粒子の平均粒径をＸμｍ、八面体マグネタイト粒子の平均粒径をＹμｍ、八面体マグネタイト粒子の存在個数率Ｚ（％）とした時、下記式（１）の値を求めた。
Ａ＝（５．２／６×πＹ3Ｚ／１００）／［（５．２／６×πＹ3Ｚ／１００）＋（５．２／６×πＸ3（１００−Ｚ）／１００］×１００・・・・・（１）
（４）磁気特性
東英工業製振動型磁力計ＶＳＭ−Ｐ７を用い、外部磁場７９．６ｋＡ／ｍ（＝１ｋＯｅ）、３９８ｋＡ／ｍ（＝５ｋＯｅ）にて測定した。
（５）タップ密度、安息角
Ｈｏｓｏｋａｗａ Ｍｉｃｒｏｎ社製、「Ｐｏｗｄｅｒ Ｔｅｓｔｅｒ ＴｙｐｅＰＴ−Ｅ」（商品名）を用いて、タップ密度、安息角を求めた。
【００３２】
【表１】
【表２】
【表３】
表１に示されるように、比較例１〜３の球状マグネタイト粒子は、タップ密度が高く、安息角が大きい。また、比較例４〜６の八面体マグネタイト粒子は、残留磁化が高く、安息角も大きい。
【００３６】
これに対して、実施例１〜２７のマグネタイト粒子粉末は、タップ密度が低く、安息角が小さく、しかも残留磁化も低い。
【００３７】
【発明の効果】
以上説明したように、本発明の酸化鉄粒子粉末は、流動性が高く、かつ充填密度が低く、しかも磁気特性に優れる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to iron oxide particle powder, in particular, by mixing spherical iron oxide particles and octahedral iron oxide particles having different shapes, to improve various properties such as fluidity, dispersibility, and handling properties in a well-balanced manner. In particular, the present invention relates to iron oxide particle powder mainly used for applications such as material powder for electrostatic copying magnetic toner, carrier material powder for electrostatic latent image development, and black pigment powder for paint.
[0002]
Problems to be solved by the prior art and the invention
2. Description of the Related Art Recently, iron oxide particles formed by an aqueous solution reaction have been widely used as a material for magnetic toners in electrophotographic copying machines, printers, and the like.
[0003]
Various general development characteristics are required for magnetic toners, but in recent years, with the development of electrophotography technology, especially copiers and printers using digital technology have been rapidly developed, and the required characteristics have become more sophisticated. .
[0004]
In other words, in addition to the conventional characters, output of graphics and photographs is also required. In particular, some printers having a capacity of 1200 dots per inch or more appear, and the latent image on the photoconductor becomes more dense. Is coming. Therefore, high reproducibility of fine lines in development is strongly required.
[0005]
In addition, the toner particles have been reduced in particle size, and it is required to further disperse the iron oxide particles in the resin.
[0006]
Generally, when producing a toner, a carrier, and a pigment, the iron oxide particles and the resin are measured, mixed, and kneaded. Among them, in order to improve the dispersibility, it is necessary to improve the supply to a kneader at the time of measurement or after mixing, and the mixing with a resin having a low specific gravity. On the other hand, higher resolution has been promoted, and those having low remanence have been preferred. In addition, as the particle size of the toner has been reduced, the iron oxide particles used therein also need to be reduced in particle size.
[0007]
Since the specific gravity of the iron oxide particles is heavier than the resin and may be separated at the time of mixing, even if there is vibration, if the bulk density is low, the mixing property with the low specific gravity can be improved, and Dispersibility after kneading can be improved. In addition, such a material is hardly compacted during transportation and has good handleability.
[0008]
However, it is widely known that spherical iron oxide particles generally have low remanent magnetization, but spherical products usually have a tendency to easily take close-packing and tend to have a high bulk density. there were. Various proposals have been made for improving the fluidity, but as a result, the fluidity of the powder is improved, but the bulk density tends to be further increased.
[0009]
An octahedron is a typical shape of the iron oxide particles. Octahedral iron oxide particles generally have a low bulk density, but have a higher remanent magnetization than their shapes, and have a problem in fine line reproducibility.
[0010]
Thus, iron oxide particles having high fluidity, low packing density, and excellent magnetic properties have not yet been provided.
[0011]
Accordingly, an object of the present invention is to provide an iron oxide particle powder having high fluidity, low packing density, and excellent magnetic properties.
[0012]
[Means for Solving the Problems]
As a result of the study, the present inventors have found that the above object can be achieved by mixing spherical and octahedral iron oxide particles.
[0013]
The present invention has been made based on the above findings, the spherical iron oxide particles and octahedral iron oxide particles is an acid iron particles you mixed,
The number average particle diameter is 0.15 to 0.5 μm, and the abundance ratio of octahedral iron oxide particles to the total number [octahedral iron oxide particle number / (spherical iron oxide particle number + octahedral iron oxide particle number) × 100] When the average particle size of the spherical iron oxide particles is X μm, the average particle size of the octahedral iron oxide particles is Y μm, and the abundance ratio of octahedral iron oxide particles is Z (%). And an iron oxide particle powder characterized by satisfying the following formula (1) .
10 ≦ (5.2 / 6 × πY 3 Z / 100) / [(5.2 / 6 × πY 3 Z / 100) + (5.2 / 6 × πX 3 (100−Z) / 100] × 100・ ・ ・ ・ ・ (1)
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
The iron oxide particles referred to in the present invention are preferably composed mainly of magnetite, and include those containing various effective elements such as silicon, aluminum and titanium, or those coated with these effective elements. In the following description, magnetite particles, which are typical iron oxide particles, will be described. Further, when referring to iron oxide particles or magnetite particles, it means either individual particles or their aggregates depending on the content. In addition, the iron oxide particles or the magnetite particles mean a mixture of iron oxide particles or magnetite particles having different shapes and particle diameters.
[0015]
The magnetite particle powder of the present invention is a mixture of spherical magnetite particles and octahedral magnetite particles. Here, the term “spherical” refers to those having no corners or sides and a ratio of major axis / minor axis of 1 to 1.2 when observed with a scanning electron microscope. An octahedron has a corner and a side when observed with a scanning electron microscope, and has four sides at one corner. The spherical or octahedral magnetite particles can be obtained by controlling the pH when oxidizing the ferrous hydroxide slurry.
[0016]
The magnetite particle powder of the present invention has a number average particle size of 0.15 to 0.5 μm. The ratio of the number of octahedral magnetite particles to the total number [octahedral magnetite particle number / (number of spherical magnetite particles + number of octahedral magnetite particles) × 100] is 5 to 90%, and the average of spherical magnetite particles therein is Xμm particle size, Ymyuemu an average particle size of octahedral magnetite particles when was the presence number ratio of octahedral magnetite particles Z (%), you satisfy the following formula (1).
10 ≦ (5.2 / 6 × πY 3 Z / 100 ) / [(5.2 / 6 × πY 3 Z / 100 ) + (5.2 / 6 × πX 3 ( 100− Z) / 100 ] × 100・ ・ ・ ・ ・ (1)
[0017]
Presence number ratio of the octahedral body magnetite particles, 5 to 90%, good Mashiku is 16-80%. When the abundance ratio is less than 5% or more than 90%, the effect of improving fluidity is small.
[0018]
It is not clear why the mixture of irregularly shaped particles improves the fluidity, but it is presumed that the mixture of particles having different active points has an effect of the roller principle.
[0019]
The above formula (1) is obtained by calculating the weight ratio of the octahedral particles in the magnetite particle powder from the volume and the true specific gravity when all the particles in the magnetite particle powder are considered to be spherical particles. If this formula (1) is not satisfied, that is, if the weight percentage of the octahedral magnetite particles is less than 10% by weight, the tap density becomes high, the powder being transported becomes tight, and subsequent handling becomes poor. In addition, the mixing property with the resin becomes poor.
[0020]
The magnetite particle powder of the present invention needs to have a tap density of 1.4 g / cm 3 or less. If the tap density exceeds 1.4 g / cm 3 , an increase in the packing density cannot be suppressed. The residual magnetization (σr) is preferably 8 Am 2 / kg ( emu / g ) or less in consideration of the influence of magnetic aggregation on fluidity.
[0021]
The magnetite particle powder of the present invention has a repose angle of preferably 42 ° or less, more preferably 40 ° or less, from the viewpoint of improving fluidity.
[0022]
【Example】
Hereinafter, the present invention will be specifically described based on examples and the like. In the present invention, it is important that octahedral particles and spherical particles coexist, and the present invention is not limited to such a case.
[0023]
[Comparative Example 1]
50 L of an aqueous ferrous sulfate solution containing 2.0 mol / L of Fe 2+ and 36 L of a 5.0 mol / L aqueous sodium hydroxide solution were mixed and stirred. The pH at this time was 6.5. While maintaining the slurry at 85 ° C., air at 30 liter / min was blown, and the pH was maintained at 5 to 9 to terminate the reaction. The obtained product particles were subjected to ordinary filtration, washing, drying and pulverization steps to obtain spherical magnetite particles.
[0024]
[Comparative Examples 2 and 3]
In the same reaction as in Comparative Example 1, the air blowing rate was set to 50 L / min (Comparative Example 2) and 70 L / min (Comparative Example 3) to obtain formed particles having a desired particle size. The resulting product particles were subjected to ordinary filtration, washing, drying and pulverization steps to obtain spherical magnetite particles.
[0025]
[Comparative Example 4]
50 L of an aqueous ferrous sulfate solution containing 2.0 mol / L of Fe 2+ and 40 L of a 5.2 mol / L aqueous sodium hydroxide solution were mixed and stirred. The pH at this time was 11. While maintaining the slurry at 85 ° C., air was blown at 30 liter / min to terminate the reaction at a pH of 10 or more. The obtained product particles were subjected to ordinary filtration, washing, drying and pulverization steps to obtain octahedral magnetite particles.
[0026]
[Comparative Examples 5 and 6]
In the same reaction as in Comparative Example 4, the air blowing rate was set to 40 L / min (Comparative Example 2) and 50 L / min (Comparative Example 3) to obtain formed particles having a desired particle size. The resulting product particles were subjected to usual filtration, washing, drying and pulverization steps to obtain octahedral magnetite particles.
[0027]
[Example 1]
700 g of the spherical magnetite particles of Comparative Example 1 and 300 g of the octahedral magnetite particles of Comparative Example 4 were mixed for 20 minutes using a V-type blender to obtain magnetite particle powder in which spherical magnetite particles and octahedral magnetite particles were mixed.
[0028]
[Examples 2 to 26 ]
The magnetite particles of Comparative Examples 1 to 6 were mixed using the magnetite particles having a total weight of 10 kg by a V-type blender in the same manner as in Example 1 so as to obtain the magnetite particle powders shown in Tables 2 and 3 to obtain magnetite particle powder. Was.
[0029]
[Example 27 ]
7 liters of the slurry after the reaction of Comparative Example 1 and 3 liters of the slurry after the reaction of Comparative Example 4 were mixed and processed by the usual filtration, washing, drying and pulverization steps to obtain magnetite particle powder.
[0030]
With respect to the magnetite particles of Comparative Examples 1 to 6 or the magnetite particle powders of Examples 1 to 27 obtained as described above, the following evaluation (average particle diameter, the ratio of the number of octahedral magnetite particles to the total number, the formula (1) ), The abundance of octahedral magnetite particles, magnetic properties, tap density, angle of repose). The results are shown in Tables 1 to 3.
[0031]
<Evaluation method>
(1) Photographs of 30,000 times were taken with a scanning electron microscope having an average particle diameter, 200 pieces were measured, and the number average of the magnetite particle powder was determined based on the fillet diameter. At that time, the number of octahedral magnetite particles and spherical magnetite particles was also checked. The average particle size of each shape was determined by measuring 100 shapes and measuring the number average particle size of each shape.
(2) Percentage of octahedral magnetite particles present relative to the total number Using the number of each shape checked at the time of measuring the average particle diameter of the magnetite particle powder in (1) above, the number of octahedral magnetite particles / (the number of spherical magnetite particles + The number of octahedral magnetite particles) × 100.
(3) The weight abundance of octahedral magnetite particles according to equation (1) The average particle size of spherical magnetite particles is X μm, the average particle size of octahedral magnetite particles is Y μm, and the abundance ratio Z (%) of octahedral magnetite particles is Then, the value of the following equation (1) was obtained.
A = (5.2 / 6 × πY 3 Z / 100 ) / [(5.2 / 6 × πY 3 Z / 100 ) + (5.2 / 6 × πX 3 ( 100− Z) / 100 ] × 100・ ・ ・ ・ ・ (1)
(4) using a magnetic property Toei Kogyo vibration magnetometer VSM-P7, was measured at an external magnetic field 79.6kA / m (= 1kOe), 398kA / m (= 5kOe).
(5) Tap Density and Angle of Repose Tap density and angle of repose were determined using “Powder Tester TypePT-E” (trade name) manufactured by Hosokawa Micron.
[0032]
[Table 1]
[Table 2]
[Table 3]
As shown in Table 1, the spherical magnetite particles of Comparative Examples 1 to 3 have a high tap density and a large angle of repose. In addition, the octahedral magnetite particles of Comparative Examples 4 to 6 have high residual magnetization and a large angle of repose.
[0036]
On the other hand, the magnetite particle powders of Examples 1 to 27 have a low tap density, a small angle of repose, and a low residual magnetization.
[0037]
【The invention's effect】
As described above, the iron oxide particle powder of the present invention has high fluidity, low packing density, and excellent magnetic properties.
Claims (4)
個数平均粒径が０．１５〜０．５μｍ、かつ全個数に対する八面体酸化鉄粒子の存在個数率［八面体酸化鉄粒子個数／（球状酸化鉄粒子個数＋八面体酸化鉄粒子個数）×１００］が５〜９０％で、その中の球状酸化鉄粒子の平均粒径をＸμｍ、八面体酸化鉄粒子の平均粒径をＹμｍ、八面体酸化鉄粒子の存在個数率Ｚ（％）とした時、下記式（１）を満足することを特徴とする酸化鉄粒子粉末。
１０≦（５．２／６×πＹ 3 Ｚ／１００）／［（５．２／６×πＹ 3 Ｚ／１００）＋（５．２／６×πＸ 3 （１００−Ｚ）／１００］×１００・・・・・（１） Spherical iron oxide particles and octahedral iron oxide particles is an acid iron particles you mixed,
The number average particle diameter is 0.15 to 0.5 μm, and the abundance ratio of octahedral iron oxide particles to the total number [octahedral iron oxide particle number / (spherical iron oxide particle number + octahedral iron oxide particle number) × 100] When the average particle size of the spherical iron oxide particles is X μm, the average particle size of the octahedral iron oxide particles is Y μm, and the abundance ratio of octahedral iron oxide particles is Z (%). And iron oxide particles satisfying the following formula (1) .
10 ≦ (5.2 / 6 × πY 3 Z / 100) / [(5.2 / 6 × πY 3 Z / 100) + (5.2 / 6 × πX 3 (100−Z) / 100] × 100・ ・ ・ ・ ・ (1)
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| JP12504299A JP3600754B2 (en) | 1999-04-30 | 1999-04-30 | Iron oxide particle powder |
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| JP12504299A JP3600754B2 (en) | 1999-04-30 | 1999-04-30 | Iron oxide particle powder |
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| EP2884339A1 (en) * | 2012-08-08 | 2015-06-17 | Canon Kabushiki Kaisha | Magnetic carrier and two-component developer |
| JP7346613B2 (en) * | 2021-01-29 | 2023-09-19 | キヤノン株式会社 | magnetic toner |
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